1. Field of the Invention
The invention relates to an assembly comprising two coaxial bodies of revolution which are made of materials possessing distinctly different thermal coefficients of linear expansion and which are connected together by fixing means, and also relates to a method of assembling these parts. In particular the invention relates to the fixing of the discharge cone of a turbojet engine to the exhaust casing, the discharge cone being made of a composite ceramic material and the exhaust casing being made of metal.
2. Summary of the Prior Art
The advantages derived from the utilisation of certain so called composite materials, particularly of the ceramic type, and due to their low density and their behaviour at the high temperatures that are sometimes required, are well known in aeronautical engineering, particularly by engine designers. However, the sometimes desirable combination of one part made of a composite material with another part made of metal, and their fixing to each other, such as in the case of the fixing of the discharge cone to the exhaust casing of a turbojet engine, requires connection means suited to the severe operating conditions due, on one hand, to the high temperature environment, and on the other hand, to the alternating stresses induced by differential expansion.
U.S. Pat. No. 4,452,038 proposes a solution to these problems using links and fixing axles. However, its implementation involves assembly difficulties, imposing very close tolerances which make manufacture expensive. Furthermore, in operation, excessive play has also been observed, due to the friction induced by the relative movements.